Newsgroups: comp.lang.c++
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!csn!arrayb!wicklund
From: wicklund@intellistor.com (Tom Wicklund)
Subject: Re: How to define a List class
Message-ID: <1991Jun11.172115.2804@intellistor.com>
Organization: Intellistor
References: <350001@hpgnd.grenoble.hp.com> <28539115.4D91@tct.com>
Date: Tue, 11 Jun 91 17:21:15 GMT

In <28539115.4D91@tct.com> chip@tct.com (Chip Salzenberg) writes:

>According to jr@hpgnd.grenoble.hp.com (Jean-Ren BOUVIER):
>>I'm looking for ideas in the classical area of "list"  packages.  ...
>>
>>I DON'T want to  consider  solutions  based on  templates  (List<Object>
>>types) or generic classes - as I don't want to replicate code.

>Well, then, you've got very few alternatives.  In C++, you cannot have
>all three of minimal-code polymorphism, type safety and involiate base
>classes.  That is because the three approaches to the downcasting
>problem fall short in one way or another:


I think what's desired (and should be implementable) is a way to
define a list class using templates and have the compiler be smart
enough to create a single implementation for the list methods.  This
should be possible by having additional information (such as a pointer
to the copy constructor for the item being placed in the list) passed
into member functions -- doable but not common in today's compiler
technology.